Unverified Commit 2ef435a8 authored by Max Kellermann's avatar Max Kellermann Committed by Christian Brauner
Browse files

fs: add might_sleep() annotation to iput() and more 



When iput() drops the reference counter to zero, it may sleep via
inode_wait_for_writeback().  This happens rarely because it's usually
the dcache which evicts inodes, but really iput() should only ever be
called in contexts where sleeping is allowed.  This annotation allows
finding buggy callers.

Additionally, this patch annotates a few low-level functions that can
call iput() conditionally.

Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: default avatarMax Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/20250917153632.2228828-1-max.kellermann@ionos.com


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent cde560f9

fs/inode.c

+18 −0
Original line number Diff line number Diff line
@@ -1279,6 +1279,8 @@ struct inode *inode_insert5(struct inode *inode, unsigned long hashval, 
	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);

	struct inode *old;



	might_sleep();



again:

	spin_lock(&inode_hash_lock);

	old = find_inode(inode->i_sb, head, test, data, true);
@@ -1382,6 +1384,8 @@ struct inode *iget5_locked_rcu(struct super_block *sb, unsigned long hashval, 
	struct hlist_head *head = inode_hashtable + hash(sb, hashval);

	struct inode *inode, *new;



	might_sleep();



again:

	inode = find_inode(sb, head, test, data, false);

	if (inode) {
@@ -1422,6 +1426,9 @@ struct inode *iget_locked(struct super_block *sb, unsigned long ino) 
{

	struct hlist_head *head = inode_hashtable + hash(sb, ino);

	struct inode *inode;



	might_sleep();



again:

	inode = find_inode_fast(sb, head, ino, false);

	if (inode) {
@@ -1605,6 +1612,9 @@ struct inode *ilookup5(struct super_block *sb, unsigned long hashval, 
		int (*test)(struct inode *, void *), void *data)

{

	struct inode *inode;



	might_sleep();



again:

	inode = ilookup5_nowait(sb, hashval, test, data);

	if (inode) {
@@ -1630,6 +1640,9 @@ struct inode *ilookup(struct super_block *sb, unsigned long ino) 
{

	struct hlist_head *head = inode_hashtable + hash(sb, ino);

	struct inode *inode;



	might_sleep();



again:

	inode = find_inode_fast(sb, head, ino, false);
@@ -1780,6 +1793,8 @@ int insert_inode_locked(struct inode *inode) 
	ino_t ino = inode->i_ino;

	struct hlist_head *head = inode_hashtable + hash(sb, ino);



	might_sleep();



	while (1) {

		struct inode *old = NULL;

		spin_lock(&inode_hash_lock);
@@ -1826,6 +1841,8 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval, 
{

	struct inode *old;



	might_sleep();



	inode->i_state |= I_CREATING;

	old = inode_insert5(inode, hashval, test, NULL, data);
@@ -1908,6 +1925,7 @@ static void iput_final(struct inode *inode) 
 */

void iput(struct inode *inode)

{

	might_sleep();

	if (unlikely(!inode))

		return;